Need Help!- Need help with 906 vmc

[CNCTECHNICIAN1]

Does anyone have any prints for the spindel of a fadal vmc 906. I am trying to drop the spindle out for rebuild and it doesn't want to come out unless i take the pulley off. I don't have prints that would indicate how i would do this. It looks like it should be keyed but I don't have slots in the shaft to indicate that it would have them. Also there are no bolts for a compression type coupling. So if you have prints or advice please let me know.
Thanks
Matt

[sti2011]

If memory serves me correct when we had a spindle pulley replaced awhile back.......It was a thermal fit. There may be a key or other type of dive mechanism somewhere. But I do remotely remembering the tech take a couple of torches to the aluminum pulley on our VMC4020 (six belt system)

[CNCTECHNICIAN1]

Originally Posted by sti2011 If memory serves me correct when we had a spindle pulley replaced awhile back.......It was a thermal fit. There may be a key or other type of dive mechanism somewhere. But I do remotely remembering the tech take a couple of torches to the aluminum pulley on our VMC4020 (six belt system)

You are correct sir. I just talked to someone at Fadal or a distributor of Fadal and they said the same thing guess i will get out the torch but do speed things up i am gonna pack the draw tube area with dry ice and shrink the spindle while I heat the pulley. I have resleeved engines this way and it save on the relentless beating. IT has been awhile since i have worked on the old Fadals.
Thanks for your help
Matt

[cnctechguru]

Have not worked with a vmc 906, but have extensive work completed on vmc 4020 and vmc 6030 machines. From the spindles that I have changed (10K rpm, posi drive belt system) it is important to make sure that you line up the timing marks on the pulley to the mark on the spindle shaft. I believe the are three marks on the pulley. This alignment is dependant on which tool changer you have. And, when you have the spindle back in and ready for the pulley, you have to make sure that you have the pulley set to the proper height. I have a piece of flat bar that is machined to a height of 1.668". (Not sure if this is the same for the six belt vs. pozi belt)Set that on the casting of the z-axis, and then heat up the pulley. Slide pulley onto shaft, and let it rest on the flat bar until it is cool. I recommend locking the spindle so it cannot rotate. This makes it easier to get you marks to align properly, before the puley cools, and you cannot rotate the pulley. Good Luck, Eric

[CNCTECHNICIAN1]

Yeah that sounds right like a good tech i am ahead of you on the marks for the tool changer but thanks for mentioning it. You can't even imagine how much heck that thing gave me getting it off with out destroying the pulley. I used dry ice in the spindel and heated the crap out of the pulley with a propane torch and still had to use a flywheel puller to get it off and it came off hard the entire way out it is going to be fun lining those marks up for reassembly. It is a posi belt set up. 10k spindel and it looks like the pulley was dead flush with the top of the spindle so that should be a no pretty simple there.
Thanks for your input
Matt

Originally Posted by cnctechguru Have not worked with a vmc 906, but have extensive work completed on vmc 4020 and vmc 6030 machines. From the spindles that I have changed (10K rpm, posi drive belt system) it is important to make sure that you line up the timing marks on the pulley to the mark on the spindle shaft. I believe the are three marks on the pulley. This alignment is dependant on which tool changer you have. And, when you have the spindle back in and ready for the pulley, you have to make sure that you have the pulley set to the proper height. I have a piece of flat bar that is machined to a height of 1.668". (Not sure if this is the same for the six belt vs. pozi belt)Set that on the casting of the z-axis, and then heat up the pulley. Slide pulley onto shaft, and let it rest on the flat bar until it is cool. I recommend locking the spindle so it cannot rotate. This makes it easier to get you marks to align properly, before the puley cools, and you cannot rotate the pulley. Good Luck, Eric

[carbidecraters]

Man I wouldnt have used dry ice! The aluminum will just shrink. Now when you install it you must cool it quickly or you will damage the front bearing seal on the spindle motor and ruin the motor. Fadal had a tech bulletin on this years ago.

[CNCTECHNICIAN1]

No way man. The dry ice shrinks the spindle shaft and then you heat the aluminum the aluminum heats fast while the dry ice freezes the shaft of the spindle. So your shaft will be shrunk while the aluminum expands from the heat. This has been used for years while resleeving engines. Usually the sleeves of engines are interference fit much like this pulley. It is aprox. .003-.005 interference fit. When you want to remove the sleeve you just put dry ice on the inside of the sleeve and heat the aluminum jug (same thing I did here but with a spindle. This baby is belt driven so there is no worries about the spindle motor seals. The poor mans way to install the sleeve is to freeze the sleeve in a deep freeze and then heat the block but you only have a limited amount of time do do this and get it right instantly.

[carbidecraters]

And so while your trying to shrink a hardened steel spindle with a very miniscule thermal contraction rate your trying to heat the aluminum around it..LOL I have never ever seen a Fadal tech do it that way. They use a small MAP gas torch and viola its off. I have never heard of sleeving a cast iron block with dry ice on the sleeve. You would shock load the material and add more martensite and if its cast (which it should be if its a sleeve for a cylinder) you will have micro cracks. That is if you let the temp drop too fast.

I stand behind what I said about just using a torch. Fadal tech cool the pulley down rapidly after installation becasue the heat travels up the main shaft and ruins the motor.

[scadvice]

...If you really want to get techinical about it look up the coeff. of expansion for each material, coeff. of heat transmission, and the heat capacity in btu's. Then work out all the math (budda bing... budda bang) and you will come to the same conclusion as Carbide and I... that it is easier and safer just to heat the aluminum pully. The hole will be bigger and cool on insertion slower.
Steve

[CNCTECHNICIAN1]

I did try the heat thing first and could not budge it. So you are saying that a tech from fadal would only use heat and he would just remove it by hand or using a puller??? I do see your point and no i am not going to figure out the numbers thats to much work. Either way I had success with what i did without damaging the pulley so that is what counts for now.

[scadvice]

Originally Posted by CNCTECHNICIAN1 I did try the heat thing first and could not budge it. So you are saying that a tech from fadal would only use heat and he would just remove it by hand or using a puller??? I do see your point and no i am not going to figure out the numbers thats to much work. Either way I had success with what i did without damaging the pulley so that is what counts for now.

...That is what counts in the long run

Steve

[carbidecraters]

Probly didnt get it hot enough at first but hey cool you got it off!